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Message-Id: <20080514183837.460ba848.akpm@linux-foundation.org>
Date: Wed, 14 May 2008 18:38:37 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Harvey Harrison <harvey.harrison@...il.com>
Cc: David Woodhouse <dwmw2@...radead.org>,
Al Viro <viro@...IV.linux.org.uk>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mtd: mtdchar.c silence sparse warning
On Wed, 14 May 2008 18:22:10 -0700 Harvey Harrison <harvey.harrison@...il.com> wrote:
> The copy_to_user was casting away the address space to get the offset
> of the length member. Use offsetof() instead and add it to the void __user *argp.
>
> drivers/mtd/mtdchar.c:527:23: warning: cast removes address space of expression
> drivers/mtd/mtdchar.c:527:23: warning: incorrect type in argument 1 (different address spaces)
> drivers/mtd/mtdchar.c:527:23: expected void [noderef] <asn:1>*to
> drivers/mtd/mtdchar.c:527:23: got unsigned int *<noident>
>
> Signed-off-by: Harvey Harrison <harvey.harrison@...il.com>
> ---
> drivers/mtd/mtdchar.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mtd/mtdchar.c b/drivers/mtd/mtdchar.c
> index 5d3ac51..3522d4a 100644
> --- a/drivers/mtd/mtdchar.c
> +++ b/drivers/mtd/mtdchar.c
> @@ -524,7 +524,7 @@ static int mtd_ioctl(struct inode *inode, struct file *file,
> if (ops.oobretlen > 0xFFFFFFFFU)
> ret = -EOVERFLOW;
> retlen = ops.oobretlen;
> - if (copy_to_user(&((struct mtd_oob_buf *)argp)->length,
> + if (copy_to_user(argp + offsetof(struct mtd_oob_buf, length),
> &retlen, sizeof(buf.length)))
> ret = -EFAULT;
Cleaner would be:
struct mtd_oob_buf __user *user_mtd_oob_buf = argp;
if (copy_to_user(&user_mtd_oob_buf->length, ...
?
(cleaner, faster and shorter would be put_user(), but that's off-topic).
--
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